Apparatus capable of performing both block-matching motion compensation and global motion compensation and method thereof

Abstract

An interpolation unit receives an incoming video bit stream comprising a plurality of frames including first macroblocks encoded using block-matching motion compensation and second macroblocks encoded using global motion compensation. A translation unit converts global motion parameters included in a current frame of the incoming video bit stream into a global motion vector. The interpolation unit performs luminance and chrominance interpolation operations on each macroblock contained in each frame of the incoming video bit stream. When processing a current macroblock, if the current macroblock is encoded using global motion compensation, the interpolation unit performs the luminance interpolation operations according to the global motion vector at half-pel resolution, and performs the chrominance interpolation operations at quarter-pel resolution. If the current macroblock is encoded using block-matching motion compensation, the interpolation unit performs the luminance and chrominance interpolation operations according to the macroblock motion vector contained in the current macroblock at half-pel resolution.

What is claimed is: 
     
       1. A video decoding apparatus for decoding a coded bitstream having both macroblocks encoded using block-matching motion compensation and macroblocks encoded using global-matching motion compensation, comprising:
 a macroblock motion vector storage for storing a macroblock motion vector received from the coded bitstream; 
 a translation unit for generating a global motion vector from a global motion parameter received from the coded bitstream; 
 a global macroblock motion vector storage for storing the global motion vector; 
 an interpolation unit for generating a predicted image based on the macroblock motion vector and a decoded image when a current macroblock received from the coded bitstream is encoded using block-matching motion compensation, wherein the same interpolation unit is also used for generating another predicted image based on the global motion vector and the decoded image when the current macroblock received from the coded bitstream is encoded using global-matching motion compensation instead of using the global motion parameter received from the coded bitstream. 
 
     
     
       2. The video decoding apparatus of  claim 1 , wherein the macroblock motion vector storage only stores luminance macroblock motion vectors, and the video decoding apparatus further comprises a calculator for calculating chrominance motion vectors according to the luminance macroblocks. 
     
     
       3. The video decoding apparatus of  claim 1 , wherein the interpolation unit performs half-pel bilinear interpolation calculation if the current macroblock received from the coded bitstream is encoded using block-matching motion compensation. 
     
     
       4. The video decoding apparatus of  claim 3 , wherein the global motion vector derived from the global motion parameter is the same to all pixels in a frame, and the interpolation unit is operated on a per-macroblock basis for each macroblock instead of performing global motion compensation on a per-pixel basis. 
     
     
       5. The video decoding apparatus of  claim 4 , wherein the interpolation unit performs chrominance interpolation for the current macroblock with a quarter-pel resolution if the current macroblock received from the coded bitstream is encoded using global-matching motion compensation. 
     
     
       6. The video decoding apparatus of  claim 1 , wherein the coded bitstream is a MPEG-4 compliant coded video bit stream. 
     
     
       7. The video decoding apparatus of  claim 6 , wherein the parameter no_of_sprite_warping_point of the MPEG-4 compliant coded video bit stream is set as zero or one. 
     
     
       8. The video decoding apparatus of  claim 1 , further comprising a frame memory for supplying the decoded image to the interpolation unit wherein the decoded image is a reference image under an inter-frame coding scheme. 
     
     
       9. The video decoding apparatus of  claim 1 , wherein a major portion of hardware of the interpolation unit is shared for decoding the current macroblock encoded for both the global-matching motion compensation and the block-matching motion compensation. 
     
     
       10. The video decoding apparatus of  claim 1 , wherein the video decoding apparatus only needs one interpolation unit instead of two sets of interpolation for decoding the current macroblock encoded by the global-matching motion compensation and the block-matching motion compensation respectively.